Convergent and divergent brain structural and functional abnormalities associated with developmental dyslexia

Brain abnormalities in the reading network have been repeatedly reported
in individuals with developmental dyslexia (DD); however, it is still not
totally understood where the structural and functional abnormalities are
consistent/inconsistent across languages. In the current multimodal
meta-analysis, we found convergent structural and functional alterations
in the left superior temporal gyrus across languages, suggesting a neural
signature of DD. We found greater reduction in grey matter volume and
brain activation in the left inferior frontal gyrus in morpho-syllabic
languages (e.g. Chinese) than in alphabetic languages, and greater
reduction in brain activation in the left middle temporal gyrus and
fusiform gyrus in alphabetic languages than in morpho-syllabic languages.
These language differences are explained as consequences of being DD while
learning a specific language. In addition, we also found brain regions
that showed increased grey matter volume and brain activation, presumably
suggesting compensations and brain regions that showed inconsistent
alterations in brain structure and function. Our study provides important
insights about the etiology of DD from a cross-linguistic perspective with
considerations of consistency/inconsistency between structural and
functional alterations.